Question

What is the length of side x? If necessary, round your answer to two decimal places PLEASE HELP

Answer 1

Pythagorean theorem calculator.

You should get 20.78 (rounded) just like everyone else has, however, if you want the very exact form of this perhaps for validity or bonus points...

$20.78... = 12 \sqrt{3}$ 

Answer 2

Use the pythagorean theorem
a squared plus b squared equals c squared where c is the length of the hypotenuse and a and b are the lengths of the legs in a right triangle
c^2-b^2=31^2-23^2=432
432=a^2
a=approx 20.7846